回调函数不在返回的 Promise 内执行

Question

I have two functions that return promise. The first one provide host value, and the second one use the host value to get IP address. I can see that the first function is running without any issue. But looks like the callback function side getHostIps is not executed at all. Not sure why it happens....what's wrong with my promise function?

my promise chain:

getHostedZoneId(dns)
.then(hostZoneId => {
   getHostIps(dns, hostZoneId);
})
.then(hostIps => {
    logger.Info(hostIps); //hostIps is undefined
})
.catch(err => logger.error(err));

getHostedZoneId:

var getHostedZoneId = function(dns) {
    var params = {
        DNSName: dns,
    };
    return new Promise((resolve, reject) => {
      findHostZoneByDNS(params, function(err, data) {
            if(err) {
                reject(err);
            }
            else {
                resolve(data);
            }
        });
    });
}

getHostIps:

var getHostIps = function(dns, hostZoneId) {
    var params = {
        HostedZoneId: hostZoneId,
        StartRecordName: dns,
    };
    return new Promise((resolve, reject) => {
      findHostIps(params, function(err, data) {
           //logger.info("get there");
            if(err) {
                reject(err);
            }
            else {
                resolve(data);
            }
        });
    });
}

I logged hostIps and err and data, all of them are defined. So I am sure that the callback function inside promise is not executed. But not sure how to fix it.

Any feedback is appreciated! Thanks!

Answer 1

You have to return the promise from your then statement to complete the chain.

getHostedZoneId(dns)
.then(hostZoneId => {
   return getHostIps(dns, hostZoneId); // Add return
})
.then(hostIps => {
    logger.Info(hostIps);
})
.catch(err => logger.error(err));